Reasonable T-Values fMRI contrasts


What are reasonable T-Values to acquire for fMRI contrast analyses? For group fixed effects with four ppts, some of the clusters are as high as 50, then for single subject analyses around 35. This is with FWE > 0.05 and extent cluster threshold of 20. The task is inner-speech alongside visual word presentation, compared against a rest baseline.
I am concerned these are too high!

Yes, this seems unusually high ? Could this be explained by pecular factores (e.g. very long time series). What is the number of columns and rows of the design matrix ?


thanks again for your response! :slight_smile: The time series was roughly 1100 volumes, TR = 2.16, so not especially long. What I did notice however, is that using FWE actually boosted the T-values and cluster-sizes, the T-values were smaller when multiple comparison correction was not applied. I am wonder if the clusters have sort of merged together somehow under FWE.